Engineering Standards: ICS (International Classification for Standards)

Basics

• ICS is a convention managed by ISO and is used in many standard catalogs and documents to order standards, by grouping similar topics together. Rather like the CPC (Cooperative Patent Classification) system for patents.
• There are three segments of an ICS code.

Level 1 (Fields)

• The broadest level
• They are called fields
• Each has a 2 digit notation

Level 2 (Groups)

• Intermediate level of specificity 
• They are called groups, and are sub-divisions of the fields
• Each has a 3 digit notation

Level 3 (Sub-Groups)

• Most specific topic or object
• They are called sub-groups, and are sub-divisions of the groups
• Each has a 2 digit notation

Example

ICS Code: 43.040.20

This translates to: road vehicle engineering (as the field), road vehicle systems (as the group), and lighting, signaling and warning devises (as the sub-group).

Notice how it moves broad to specific as you move left to right.